"To start with, I probably had the idea when I was 9 or 10 years old," Thornton told WREG-TV. "I wanted [ the pool] large in the deep end but large and deep enough you could swim around it and not feel like you are trapped in a little box."

What he ended up building is a pond-sized playground made up of 320 yards of gunite, 40,000 pounds of steel rebar, rock-lined waterfalls, sprayers and, by his estimate, more than half a million gallons of water.

It didn't look like this when work started on Labor Day of 1993. The initial hole was more than 20 feet deep and lined with a polyethylene mat.

"I was 39 years old then," Thornton said, "and I thought if I ever am going to do anything like that I better get started working on it."

The only request Thornton's wife, Jane Thornton, had was to not have the pool next to the house.

"If you've seen my house I have pavement everywhere," she said. "And he wanted to put it right next to that. I told him he had to move it out some. He told me 'But it's all pasture and it runs downhill,' and I said, 'You're smart enough, you can figure it out.'"

The pool was made for the family but grew to be much more than that, welcoming their kids' soccer teams, birthday parties, weddings and even the Japanese National baseball team.

"They called and asked if we could have them over for an afternoon," recalled Mrs. Thornton. "I thought sure, I thought there are nine guys on the field, probably a total of 25 people. Wrong. There was 50."

In 1998 and '99 the Thorntons replaced the rubber liner and added a waterfall and most of the rock decoration, but it only lasted 15 years. In 2013 they updated the pool to its current appearance.

Thornton had to create his own filtration system from the start, one that is more effective and efficient.